In fact, "A Patriot's History of the United States" has numerous errors that are difficult to explain. For example, in just two paragraphs about the Reagan tax cuts, the book puts forward three numbers and gets all three of them wrong. You can see a description of these errors at http://www.freerepublic.com/focus/f-news/1338034/posts?q=1&&page=51#59, along with a response from Larry Schweikart, one of the authors.

In fact, they are not wrong, except that the impact of the tax cuts may be way understated. The authors claimed revenues grew 40% and they, apparently were conservative: revenues grew WAY more than 40%.